The purpose of this study is to determine whether improved outdoor time has an effect on the onset and progression of myopia in children.

1. To evaluate the effect of increased time outdoors on the incidence of myopia in non-myopic children;
2. To evaluate the effect of increased time outdoors on the progression of myopia in myopic children;
3. To explore if there is dose-response effect of time outdoors on the incidence and progression of myopia.

Inclusion Criteria:

1. at baseline be enrolled in grade 1 and 2 of primary schools;
2. have a parent or guardian who is able to read and comprehend Mandarin and give informed consent as demonstrated by signing a record of informed consent;
3. Children verbally consent when registration for examination

Exclusion Criteria:

1. Any systemic or ocular pathology that may affect the refractive error status of the eye;
2. Strabismus and amblyopia;
3. Intellectual disability;
4. Using any anti-myopia treatments (orthokeratology, atropine, accommodation function training, acupuncture, auricular point sticking, progressive addition spectacle lenses or other anti-myopia contact lenses).
5. Not suitable for inclusion in the study as deemed by the investigator.